No, full speed Thunderbolt 3 cables (40 Gbit/sec) that are 1m or longer can't support both full 40 Gbit/s Thunderbolt 3 speeds and USB 3.0/3.1 speeds. They and are limited to USB 2.0 when connected to USB devices. That is simply due to the physical limitations of the spec/cable materials.

For example, this is why Belkin's 2m 40 Gbit/sec Thunderbolt 3 cable is limited to USB 2.0 speeds when connected to USB devices.

This is likely why Apple chose the rather peculiar 0.8m length. It allows this cable to have the best of all three worlds, Thunderbolt 3 speeds up to 40 Gbit/sec, USB 3.1 speeds up to 10 Gbit/sec, and full 100W of power.

I'm actually pretty impressed, as far as I'm aware this is the first cable of its kind to reach 0.8 meters and it does it without being super bulky at the end.